From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 368F936C0B6 for ; Tue, 18 Nov 2025 18:25:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763490304; cv=none; b=QB6z5NbhBrbcV1TlrVdDvY05tb9NZ3aYxzToZhCLOcsIeQ/2VoJSCmi+0iDCKz6R5EuzwYxdNSFwIuvLGI78XIyX2fcuhqh+4tASWbfRt25bIBm3vEso41aEggRDmSiwPidvLctCCGqhgWLhrwSi9wpseyF6lH7n/5CVruH0aYc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763490304; c=relaxed/simple; bh=euFA8Gpbxb444t3Sk88pL+hmZnDfk8DfBXd/0vmiFEo=; h=Date:From:To:cc:Subject:In-Reply-To:Message-ID:References: MIME-Version:Content-Type; b=XLDSIW3khskhuSe2xTGuRyphQK4w0tkeZETLybDTztdB9G+jgr/sr+bWWxi1lVlv+13fhwZiJG/5pygnF13ZtxXaZK0VfmJBsarILQq8ivSWxIJJ4JtjkX+t9zDgqnKpaSafTklj5KZBpV/17vHe2fZXwl12oTqYNkXjiT4veg8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=bjzPWnY7; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="bjzPWnY7" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1763490301; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=W6S9yyzsxSw09DD49kBELj6v4WeMmTrKl8rTtJFc2Jc=; b=bjzPWnY7sK1VMxzyyQyZgKrh33b1xqACcRu8s2VB6fW/K0FxtCySA8EwN7VIoIxOhQJ2sl VxBEdq/55sUrBMB6r0URJHTAIT2Hcs0/2JTdOJdxLfD1DvK3XQBRGO9u90WbOJyKBZZ5oN RVvKA1mknmzFAlGvDCIKjMtDNx8ceTU= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-541-1XtSCEMdNxGSGNJYbCpcvg-1; Tue, 18 Nov 2025 13:24:56 -0500 X-MC-Unique: 1XtSCEMdNxGSGNJYbCpcvg-1 X-Mimecast-MFC-AGG-ID: 1XtSCEMdNxGSGNJYbCpcvg_1763490295 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id A0B13180048E; Tue, 18 Nov 2025 18:24:54 +0000 (UTC) Received: from [10.44.32.60] (unknown [10.44.32.60]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id EB2A1195608E; Tue, 18 Nov 2025 18:24:52 +0000 (UTC) Date: Tue, 18 Nov 2025 19:24:49 +0100 (CET) From: Mikulas Patocka To: kernel test robot cc: Dongsheng Yang , oe-kbuild-all@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: include/linux/fortify-string.h:571:4: warning: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? In-Reply-To: <202511171758.8thF02dJ-lkp@intel.com> Message-ID: <1aebcf4a-0d88-014e-18a4-fe36e528dd35@redhat.com> References: <202511171758.8thF02dJ-lkp@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Hi Would you explain what's wrong there? at drivers/md/dm-pcache/cache_key.c:816 there's cache_pos_copy(&cache->key_head, pos); cache_pos_copy is defined as: static inline void cache_pos_copy(struct pcache_cache_pos *dst, struct pcache_cache_pos *src) { memcpy(dst, src, sizeof(struct pcache_cache_pos)); } cache->key_head has the type struct pcache_cache_pos pos has the type struct pcache_cache_pos * pos points to the local variable pos_tail, that has the type pcache_cache_pos. So, I don't see any access beyond end of structure there. Am I missing something? Mikulas On Mon, 17 Nov 2025, kernel test robot wrote: > tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master > head: 6a23ae0a96a600d1d12557add110e0bb6e32730c > commit: 1d57628ff95b32d5cfa8d8f50e07690c161e9cf0 dm-pcache: add persistent cache target in device-mapper > date: 3 months ago > config: riscv-randconfig-r113-20251117 (https://download.01.org/0day-ci/archive/20251117/202511171758.8thF02dJ-lkp@intel.com/config) > compiler: riscv64-linux-gcc (GCC) 9.5.0 > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251117/202511171758.8thF02dJ-lkp@intel.com/reproduce) > > If you fix the issue in a separate patch/commit (i.e. not just a new version of > the same patch/commit), kindly add following tags > | Reported-by: kernel test robot > | Closes: https://lore.kernel.org/oe-kbuild-all/202511171758.8thF02dJ-lkp@intel.com/ > > All warnings (new ones prefixed by >>): > > In file included from include/linux/string.h:382, > from include/linux/bitmap.h:13, > from include/linux/cpumask.h:12, > from include/linux/smp.h:13, > from include/linux/lockdep.h:14, > from include/linux/spinlock.h:63, > from include/linux/sched.h:37, > from include/linux/mempool.h:8, > from include/linux/bio.h:8, > from drivers/md/dm-pcache/segment.h:5, > from drivers/md/dm-pcache/cache.h:5, > from drivers/md/dm-pcache/cache_key.c:2: > In function 'fortify_memcpy_chk', > inlined from 'cache_pos_copy' at drivers/md/dm-pcache/cache.h:403:2, > inlined from 'cache_replay' at drivers/md/dm-pcache/cache_key.c:816:2: > >> include/linux/fortify-string.h:571:4: warning: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Wattribute-warning] > 571 | __write_overflow_field(p_size_field, size); > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > > vim +/__write_overflow_field +571 include/linux/fortify-string.h > > a28a6e860c6cf2 Francis Laniel 2021-02-25 515 > f68f2ff91512c1 Kees Cook 2021-04-20 516 /* > f68f2ff91512c1 Kees Cook 2021-04-20 517 * To make sure the compiler can enforce protection against buffer overflows, > f68f2ff91512c1 Kees Cook 2021-04-20 518 * memcpy(), memmove(), and memset() must not be used beyond individual > f68f2ff91512c1 Kees Cook 2021-04-20 519 * struct members. If you need to copy across multiple members, please use > f68f2ff91512c1 Kees Cook 2021-04-20 520 * struct_group() to create a named mirror of an anonymous struct union. > f68f2ff91512c1 Kees Cook 2021-04-20 521 * (e.g. see struct sk_buff.) Read overflow checking is currently only > f68f2ff91512c1 Kees Cook 2021-04-20 522 * done when a write overflow is also present, or when building with W=1. > f68f2ff91512c1 Kees Cook 2021-04-20 523 * > f68f2ff91512c1 Kees Cook 2021-04-20 524 * Mitigation coverage matrix > f68f2ff91512c1 Kees Cook 2021-04-20 525 * Bounds checking at: > f68f2ff91512c1 Kees Cook 2021-04-20 526 * +-------+-------+-------+-------+ > f68f2ff91512c1 Kees Cook 2021-04-20 527 * | Compile time | Run time | > f68f2ff91512c1 Kees Cook 2021-04-20 528 * memcpy() argument sizes: | write | read | write | read | > f68f2ff91512c1 Kees Cook 2021-04-20 529 * dest source length +-------+-------+-------+-------+ > f68f2ff91512c1 Kees Cook 2021-04-20 530 * memcpy(known, known, constant) | y | y | n/a | n/a | > f68f2ff91512c1 Kees Cook 2021-04-20 531 * memcpy(known, unknown, constant) | y | n | n/a | V | > f68f2ff91512c1 Kees Cook 2021-04-20 532 * memcpy(known, known, dynamic) | n | n | B | B | > f68f2ff91512c1 Kees Cook 2021-04-20 533 * memcpy(known, unknown, dynamic) | n | n | B | V | > f68f2ff91512c1 Kees Cook 2021-04-20 534 * memcpy(unknown, known, constant) | n | y | V | n/a | > f68f2ff91512c1 Kees Cook 2021-04-20 535 * memcpy(unknown, unknown, constant) | n | n | V | V | > f68f2ff91512c1 Kees Cook 2021-04-20 536 * memcpy(unknown, known, dynamic) | n | n | V | B | > f68f2ff91512c1 Kees Cook 2021-04-20 537 * memcpy(unknown, unknown, dynamic) | n | n | V | V | > f68f2ff91512c1 Kees Cook 2021-04-20 538 * +-------+-------+-------+-------+ > f68f2ff91512c1 Kees Cook 2021-04-20 539 * > f68f2ff91512c1 Kees Cook 2021-04-20 540 * y = perform deterministic compile-time bounds checking > f68f2ff91512c1 Kees Cook 2021-04-20 541 * n = cannot perform deterministic compile-time bounds checking > f68f2ff91512c1 Kees Cook 2021-04-20 542 * n/a = no run-time bounds checking needed since compile-time deterministic > f68f2ff91512c1 Kees Cook 2021-04-20 543 * B = can perform run-time bounds checking (currently unimplemented) > f68f2ff91512c1 Kees Cook 2021-04-20 544 * V = vulnerable to run-time overflow (will need refactoring to solve) > f68f2ff91512c1 Kees Cook 2021-04-20 545 * > f68f2ff91512c1 Kees Cook 2021-04-20 546 */ > 54d9469bc515dc Kees Cook 2021-06-24 547 __FORTIFY_INLINE bool fortify_memcpy_chk(__kernel_size_t size, > f68f2ff91512c1 Kees Cook 2021-04-20 548 const size_t p_size, > f68f2ff91512c1 Kees Cook 2021-04-20 549 const size_t q_size, > f68f2ff91512c1 Kees Cook 2021-04-20 550 const size_t p_size_field, > f68f2ff91512c1 Kees Cook 2021-04-20 551 const size_t q_size_field, > 475ddf1fce1ec4 Kees Cook 2023-04-07 552 const u8 func) > a28a6e860c6cf2 Francis Laniel 2021-02-25 553 { > a28a6e860c6cf2 Francis Laniel 2021-02-25 554 if (__builtin_constant_p(size)) { > f68f2ff91512c1 Kees Cook 2021-04-20 555 /* > f68f2ff91512c1 Kees Cook 2021-04-20 556 * Length argument is a constant expression, so we > f68f2ff91512c1 Kees Cook 2021-04-20 557 * can perform compile-time bounds checking where > fa35198f39571b Kees Cook 2022-09-19 558 * buffer sizes are also known at compile time. > f68f2ff91512c1 Kees Cook 2021-04-20 559 */ > f68f2ff91512c1 Kees Cook 2021-04-20 560 > f68f2ff91512c1 Kees Cook 2021-04-20 561 /* Error when size is larger than enclosing struct. */ > fa35198f39571b Kees Cook 2022-09-19 562 if (__compiletime_lessthan(p_size_field, p_size) && > fa35198f39571b Kees Cook 2022-09-19 563 __compiletime_lessthan(p_size, size)) > a28a6e860c6cf2 Francis Laniel 2021-02-25 564 __write_overflow(); > fa35198f39571b Kees Cook 2022-09-19 565 if (__compiletime_lessthan(q_size_field, q_size) && > fa35198f39571b Kees Cook 2022-09-19 566 __compiletime_lessthan(q_size, size)) > a28a6e860c6cf2 Francis Laniel 2021-02-25 567 __read_overflow2(); > f68f2ff91512c1 Kees Cook 2021-04-20 568 > f68f2ff91512c1 Kees Cook 2021-04-20 569 /* Warn when write size argument larger than dest field. */ > fa35198f39571b Kees Cook 2022-09-19 570 if (__compiletime_lessthan(p_size_field, size)) > f68f2ff91512c1 Kees Cook 2021-04-20 @571 __write_overflow_field(p_size_field, size); > f68f2ff91512c1 Kees Cook 2021-04-20 572 /* > f68f2ff91512c1 Kees Cook 2021-04-20 573 * Warn for source field over-read when building with W=1 > f68f2ff91512c1 Kees Cook 2021-04-20 574 * or when an over-write happened, so both can be fixed at > f68f2ff91512c1 Kees Cook 2021-04-20 575 * the same time. > f68f2ff91512c1 Kees Cook 2021-04-20 576 */ > fa35198f39571b Kees Cook 2022-09-19 577 if ((IS_ENABLED(KBUILD_EXTRA_WARN1) || > fa35198f39571b Kees Cook 2022-09-19 578 __compiletime_lessthan(p_size_field, size)) && > fa35198f39571b Kees Cook 2022-09-19 579 __compiletime_lessthan(q_size_field, size)) > f68f2ff91512c1 Kees Cook 2021-04-20 580 __read_overflow2_field(q_size_field, size); > a28a6e860c6cf2 Francis Laniel 2021-02-25 581 } > f68f2ff91512c1 Kees Cook 2021-04-20 582 /* > f68f2ff91512c1 Kees Cook 2021-04-20 583 * At this point, length argument may not be a constant expression, > f68f2ff91512c1 Kees Cook 2021-04-20 584 * so run-time bounds checking can be done where buffer sizes are > f68f2ff91512c1 Kees Cook 2021-04-20 585 * known. (This is not an "else" because the above checks may only > f68f2ff91512c1 Kees Cook 2021-04-20 586 * be compile-time warnings, and we want to still warn for run-time > f68f2ff91512c1 Kees Cook 2021-04-20 587 * overflows.) > f68f2ff91512c1 Kees Cook 2021-04-20 588 */ > f68f2ff91512c1 Kees Cook 2021-04-20 589 > f68f2ff91512c1 Kees Cook 2021-04-20 590 /* > f68f2ff91512c1 Kees Cook 2021-04-20 591 * Always stop accesses beyond the struct that contains the > f68f2ff91512c1 Kees Cook 2021-04-20 592 * field, when the buffer's remaining size is known. > 311fb40aa0569a Kees Cook 2022-09-02 593 * (The SIZE_MAX test is to optimize away checks where the buffer > f68f2ff91512c1 Kees Cook 2021-04-20 594 * lengths are unknown.) > f68f2ff91512c1 Kees Cook 2021-04-20 595 */ > 475ddf1fce1ec4 Kees Cook 2023-04-07 596 if (p_size != SIZE_MAX && p_size < size) > 3d965b33e40d97 Kees Cook 2023-04-07 597 fortify_panic(func, FORTIFY_WRITE, p_size, size, true); > 475ddf1fce1ec4 Kees Cook 2023-04-07 598 else if (q_size != SIZE_MAX && q_size < size) > 94fd44648dae2a Kees Cook 2025-07-29 599 fortify_panic(func, FORTIFY_READ, q_size, size, true); > 54d9469bc515dc Kees Cook 2021-06-24 600 > 54d9469bc515dc Kees Cook 2021-06-24 601 /* > 54d9469bc515dc Kees Cook 2021-06-24 602 * Warn when writing beyond destination field size. > 54d9469bc515dc Kees Cook 2021-06-24 603 * > 2003e483a81cc2 Kees Cook 2024-06-19 604 * Note the implementation of __builtin_*object_size() behaves > 54d9469bc515dc Kees Cook 2021-06-24 605 * like sizeof() when not directly referencing a flexible > 54d9469bc515dc Kees Cook 2021-06-24 606 * array member, which means there will be many bounds checks > 54d9469bc515dc Kees Cook 2021-06-24 607 * that will appear at run-time, without a way for them to be > 54d9469bc515dc Kees Cook 2021-06-24 608 * detected at compile-time (as can be done when the destination > 54d9469bc515dc Kees Cook 2021-06-24 609 * is specifically the flexible array member). > 54d9469bc515dc Kees Cook 2021-06-24 610 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101832 > 54d9469bc515dc Kees Cook 2021-06-24 611 */ > 2003e483a81cc2 Kees Cook 2024-06-19 612 if (p_size_field != SIZE_MAX && > 54d9469bc515dc Kees Cook 2021-06-24 613 p_size != p_size_field && p_size_field < size) > 54d9469bc515dc Kees Cook 2021-06-24 614 return true; > 54d9469bc515dc Kees Cook 2021-06-24 615 > 54d9469bc515dc Kees Cook 2021-06-24 616 return false; > a28a6e860c6cf2 Francis Laniel 2021-02-25 617 } > a28a6e860c6cf2 Francis Laniel 2021-02-25 618 > > :::::: The code at line 571 was first introduced by commit > :::::: f68f2ff91512c199ec24883001245912afc17873 fortify: Detect struct member overflows in memcpy() at compile-time > > :::::: TO: Kees Cook > :::::: CC: Kees Cook > > -- > 0-DAY CI Kernel Test Service > https://github.com/intel/lkp-tests/wiki >